Relation between hostility and coronary heart disease

Editor—The summary points of Hemingway and Marmot’s review of psychosocial risk factors for coronary heart disease may be misleading.1 The first of these states that “prospective cohort studies show a possible aetiological role for type A/hostility.” However, of the four prospective studies of hostility, only two show any significant association between hostility and coronary heart disease (one for women only). Six of the nine aetiological studies of type A behaviour also show no association with coronary heart disease. The other three studies give no information on completeness of follow up or whether outcomes such as angina were assessed in a blinded manner. One of these studies had minimal adjustment for confounding. No study showed any prognostic role for type A behaviour or hostility. Taken together, these studies do not represent robust evidence that these psychological variables have an important role in the development or prognosis of coronary heart disease. The authors also rightly suggest that the role of publication bias should be considered. We recently investigated this by re-examining a meta-analysis, also cited by Hemingway and Marmot, which pooled several prospective and retrospective studies of hostility and coronary heart disease and concluded that hostility was an independent risk factor.2 A funnel plot of these studies suggests publication and related biases (figure (top)), indicating underpublication of negative results. However, the apparent publication bias is more likely to be a result of poor methodological quality—in particular, inadequate adjustment for confounding in the primary studies. When we took this into account (using regression to adjust the effect sizes according to the number of variables used as adjusters in the primary study) the relation between hostility and coronary heart disease disappeared and the funnel plot became symmetrical (figure (bottom)). This supports the view that publication bias among these studies should be considered only when other sources of bias, such as the internal validity of the included studies, are taken into account, as suggested by Egger et al.3 Claims about the toxicity of type A behaviour and hostility have led to the development of behavioural “treatments” for these putative risk factors. A recent editorial also went as far as to suggest that, as hostility appeared to be a “toxic component,” we should all be nice to each other.4 Perhaps in the light of Hemingway and Marmot’s review, and the above comments, this advice should be reconsidered.